British Prime Minister Theresa May has arrived in Saudi Arabia, hoping to tap the oil-rich kingdom’s “immense potential” as she launches a diplomatic drive to boost post-Brexit investment and trade.

May landed at a military airport in Riyadh on Tuesday, coming from Jordan.

The prime minister is looking to strike new trade deals as the UK prepares to leave the European Union, with a major focus on longtime partners in the Persian Gulf.

She is trying to secure a good Brexit deal in negotiations with EU leaders. But at the same time, she is exploring other grounds in case talks collapse and Britain crashes out of the bloc without an agreement.

"I want to see the United Kingdom as a truly global Britain, outward looking, around the world, trading around the world, a good continuing deep partnership with the European Union but also trading and working with others around the world," May said Tuesday in Jordan before departing for Riyadh.

Jordan's King Abdullah II (R) talks to British Prime Minster Theresa May (2-R) during their visit to a military base, near Amman, April 3, 2017. (Photo by AFP)

The UK exported more than £6.5 billion in goods and services to Saudi Arabia in 2015, making it Britain’s largest trading partner in the Middle East.

Britain has also been one of the biggest suppliers of weapons to Riyadh for 40 years, an issue that has come under close scrutiny because of the war in Yemen, which has killed more than 12,000 people, half of them civilians.

Saudi Arabia launched the offensive against Yemen in March 2015 in an attempt to bring back the former government to power and undermine the Houthi Ansarullah movement.

May defended the British relationship with Saudi Arabia amid growing calls on her to pressure Riyadh over its military campaign in Yemen and human rights record.

The premier insisted that she had no problem raising “hard issues” with Saudi officials during her visit.

"We have no difficulty in raising hard issues with those that we meet with, be it in Saudi Arabia or elsewhere around the world," she said.

May also promised to support the people of Yemen through humanitarian aid.

Yemeni students study in a damaged classroom in the Yemeni port city of Hudaydah, on March 15, 2016. (Photo by AFP)

While in Riyadh, May is expected to hold two days of talks with senior Saudi leaders, including King Salman bin Abdulaziz and the kingdom’s powerful crown prince, Mohammed bin Nayef.

Corbyn also called on May’s government to immediately halt arms sales to Saudi Arabia and to push for a ceasefire in Yemen.

"Unless the prime minister challenges the Saudi regime over its abuses this week, it will be clear she is ready to sacrifice human rights and security on the altar of the arms trade," he said in a statement.